Waterproof siloxane cements



Patented Apr. 14 1953 WATERPROOF SILOXANE CEMENTS Pierre Jean Chevalier,Lyon, France, assignor to Societe ales Usines Chimiques Rhone-Poulenc,Paris, France, a French body corporate No Drawing. Application November28, 1949, Se-

rial No. 129,882. In France December 7, 1948 11 Claims. (01. 260-18,)

This invention relates to waterproof cements and particularly towaterproof cements based .on organosilicic resins which set at roomtemperature.

It is an object of the present invention to provide a method wherebyorganosilicic resins :may :be caused to set at room temperature. It is:a further object of the invention to provide .organosilicic resincompositions which set at room temperature, in the manner of .cements,and which are cap-able of adhering to the most varied materials.

In my copending application .No. 129581,, filed on even date herewithprocesses are described for the production of newfiuid methylpolysiloxones which have a CHszSi ratio of at most 1.4, which containonly 8 to '20 silicon atoms .in the polysiloxane molecule and which boilbetween 1-20 and 250 C. at a pressure of 8 mm. of mercury. These newfluid methyl polysi-loxanes gel at room temperature under the action ofsmall quantities, .e. g. 0.1 to 1.0% of their weight, of leadnaphthenate.

The said fluid methyl polysiloxanes :are produced by hydrolysing anethereal solution of methyl halogeno-s-ilanes having a CHarSi ratio ofat most 1-4, subjecting the product to distillation under reducedpressure and separating the fractions of a low degree of condensationwhich have a -CH3:.S;i ratio of .at most 1.4,whi'ch contain only 8 to 20,si-licon atoms in their molecules and which boil between .120 and 250C. at a pressure of -8 mm. of mercury. f

The quantity of the methyl polysiloxanes which can be separated bydistillation under reduced pressure varies according to the methodemployed tor :hydr-olysi-ng the ethereal solution of methylhalogenos-ilanes; where the hydrolysis is eilected by any of the usualmethods from 1.0% to 20% of the fluid methyl polysiloxanes are generallyobtained.

It has now been found that contrary to expectations, although fluid andonly slightly condensed, the :said fluid methyl polysiloxanes whenemployed in the place of resins in the process described in U. 18..Patent application Serial .No. 774,681, filed September 17, 1947, nowabandoned, yield cements which set at room temperature. The substitutionof the :fluid methyl polysiloxanes for the methyl polysiloxane resinsaffords important advantages. By avoiding the use of solvents thetendency for the cements to crack or blister is reduced and owing to thefluid nature of the said products they can be readily mixed withiillersand even with considerable proportions oifillers.

According to the present invention, therefore cements which set at roomtemperature com prise fluid :methyl apolysiloxanes which have .a CH31Siratio of at most 1.4, which contain only '8 to 20 silicon atoms in thepolysiloxane molecule and which boil between 120 and 250 C. at apressure of '8 mm. of mercury, a filler and an organic metal derivative.The organic metal derivative may he a sodium compound but in thepreferred form of the invention a metal derivative selected from theacetates, stearates and phenates of lead and lithium is preferred.

Cements of'particular value are those comprising the fluid methylpolysiloxane, filler and lead acetate, those comprising the fluid'methyl polysiloxane, filler and a mixture of lead 'stearate and leadphenate, and those comprising the fluid methyl polysiloxane, filler andlithium phenate.

The filler should, for preference, be present in sufficient proportionto make the cement composition into a thick paste.

The fluid methyl polysiloxane may .be employed in its normal conditionand it is unnecessary to use any solvent, with the advantage that thetendency of the cements to crack or blister is reduced.

As filler, very diverse substances such .as lead monoxide, bariumsulphate, calcium carbonate, silica, asbestos powder and the -like maybeemployed either separately or in admixture.

The quantity of metal derivative required "to produce setting at normaltemperature is very low, proportions from 0.1 to 5.0% by weight of thefluid methyl polysiloxane generally giving satisfaction. The nature ofthe metal determines the electrical properties of the cement obtained.The

porated in the fluid methyl polysiloxane.

The cement generally sets in several hours at room temperature.

The cements obtained in accordance with the present invention are veryimpermeable to water vapour and are waterproof on the surface. When themetal derivative employed to accelerate the setting is suitably chosen,they also have a high electrical resistivity. These excellent propertiesenable them to be successfully employed in the electrical,radio-electrical, vacuum and other industries. Thus for example they canbe advantageously substituted for insulating cements for sealing, basedon litharge and glycerine, which are currently employed in theelectrical industry and which have the disadvantage of being sensitiveto moisture, as a result of which they become more or less conductiveunder the action of water. They can in addition be employed as coatingson electrical parts which are likely to be deteriorated by water vapour;or as protective coverings for existing cements. Moreover, the fact thatthe cements according to the present invention set at normal temperaturepermits of applying them to materials sensitive to the action of heatand in particular to papers, cardboards, woven fabrics and the like, towhich they adhere excellently.

The following example will serve to illustrate the invention but is notto be regarded as limiting it in any way.

Example 868 parts of a mixture of methyl chlorsilanes having a CI-IstSiratio equal to 1.25, are dissolved in 1050 parts of ether and thesolution is poured into 2250 parts of water. The ethereal layer isseparated and 390 parts of resin are isolated by distilling off theether. The resin is then distilled under reduced pressure and 43 partsof a mixture of methyl polysiloxanes of a low degree of condensation areseparated under a pressure of 8 mm. of mercury, which mixture boils from120 to 250 C. at a pressure of 8 mm. of mercury. These fluid methylpolysiloxanes can be stored for a prolonged period without change inviscosity, whereas the crude resin, freed from the greater part of thesolvents contained therein, thickens and gels on keeping for severalmonths and sometimes gels after only a few weeks storage.

42 parts of fluid methyl polysiloxanes thus obtained are mixed with 58parts of barium sulphate. A mixture of lead stearate and lead phenate inbenzene solution is added in such quantity that the ratio leadzresin::521000.

The resulting cement sets in 16 hours at room temperature.

I claim:

1. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CH3:Si ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a filler inproportion sufficient to make the composition a thick 'paste and anorganic metal derivative selected from the class consisting of theacetates, stearates and phenates of lead and lithium.

2. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CHazSi ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate,

'4 the said polysiloxanes being the only siloxane compounds present, afiller in proportion sufficient to make the composition a thick pasteand lead acetate.

3. A waterproof cement composition capable of setting at normaltemperature comprising a. mixture of fluid methyl polysiloxanes whichhave a CHatSi ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from to 250 C.at a pressure of 8 mm. of mercury and which gels at room temperature inthe presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a filler inproportion sufficient to make the composition a thick paste and amixture of lead stearate and lead phenate.

4. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CH3:Si ratio of at most- 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a filler inproportion sufficient to make the composition a thick paste and lithiumphenate.

5. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CHazSi ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a mineralfiller in proportion sufiicient to make the composition a thick pasteand an organic metal derivative selected from the class consisting ofthe acetates, stearates and phenates of lead and lithium.

6. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CH3:Si ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, litharge inproportion sufficient to make the composition a thick paste and leadacetate.

'7. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CI-IstSi ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, litharge inproportion sufficient to make the composition a thick paste and amixture of lead stearate and lead phenate.

8. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CHsiSi ratio of at most 1.4, which contain only 8 to 220 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, litharge inproportion sufficient to make the composition a thick paste and lithiumphenate.

9. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CHaZSi ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a filler inproportion suflicient to make the composition a thick paste and from 0.1to 5.0% on the weight of the fluid methyl polysiloxanes of lead acetate.

10. A waterproof cement composition capable of setting at normaltemperature comprising a mixture of fluid methyl polysiloxanes whichhave a CHaZSi ratio of at most 1.4, which contain only 8 to 20 siliconatoms in the polysiloxane molecule, which mixture boils from 120 to 250C. at a pressure of 8 mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a filler inproportion sufficient to make the. composition a thick paste and from0,1 to

.C. at a pressure of 8mm. of mercury and which gels at room temperaturein the presence of small quantities of lead naphthenate, the saidpolysiloxanes being the only siloxane compounds present, a filler inproportion sufficient to make the composition a thick paste and from 0.1to 5.0% on the weight of the fluid methyl polysiloxanes of lithiumphenate.

PIERRE JEAN CHEVALIER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,258,218 Rochow Oct. 7, 1941 2,410,737 Jenny Nov. 5, 19462,418,051 Scott Mar. 25, 1947 2,449,572 Welsh Sept. 21, 1948 2,460,795Warrick Feb. 1, 1949 2,465,188 Barry et al. Mar. 22, 1949 2,499,865 IlerMar. 7, 1950 2,526,059 Zabel Oct. 17, 1950 OTHER REFERENCES Scott,Journ. Amer. Chem. Soc., March 1946, vol. 68, pp. 356 to 358,

1. A WATERPROOF CEMENT COMPOSITION CAPABLE OF SETTING AT NORMALTEMPERATURE COMPRISING A MIXTURE OF FLUID METHYL POLYSILOANES WHICH HAVEA CH3:SI RATIO OF AT MOST 1.4, WHICH CONTAIN ONLY 8 TO 20 SILICON ATOMSIN POLYSILOXANE MOLECULE, WHICH MIXTURE BOILS FROM 120 TO 250* C. AT APRESSURE OF 8MM. OF MERCURY AND WHICH GELS AT ROOM TEMPERATURE IN THETHE PRESENCE OF SMALL QUANTITIES OF LEAD NAPHTHENATE, THE SAIDPOLYSILOXANES BEING THE ONLY SILOXANE COMPOUNDS PRESENT, A FILLER INPROPORTION SUFFICIENT TO MAKE THE COMPOSITION A THICK PASTE AND ANORGANIC METAL DERIVATIVE SELECTED FROM THE CLASS CONSISTING OF THEACETATES, STEARATES AND PHENATES OF LEAD AND LITHIUM.